The present invention relates to a device for the selection of a stitch forming device in an electronic sewing machine and a built-in diagnosing device described in U.S. Pat. No. 4,480,561 assigned to the same assignee.
In methods of selecting a diagnosing device, there have been employed
(1) a method wherein an exclusive switch is provided at a position at which its actuation is difficult, and the switch is turned "on," and PA0 (2) a method wherein actuation of a specified key for the stitch forming operation is combined with a special condition (for example, an operation in which a power source is closed while a corresponding key is kept depressed).
The prior-art methods, however, have the following disadvantages: With the method (1), since a place for installing the exclusive switch must be secure, the structure of the sewing machine becomes complicated, and besides, expenses for the switch component and for the installation thereof are involved. With the method (2), since the diagnosing device is easily actuated by an erroneous operation, the sewing machine is difficult to use, and at the same time, diagnostic operations are limited lest any injury be inflicted on the user by erroneous operating steps.